Natural (-)-colchicine can easily be converted into trimethyl colchicinic acid (TMCA). The latter can be racemized in the form of its Schiff's base with KOH in methanol. Mescaline has been converted by standard procedures into a variety of N-trimethoxybenzyl and 1-trimethoxyphenyl substituted tetrahydroisoquinolines to be evaluated in vitro as antimitotic agents.